www.roanoke.com

Paws & Claws

Jill Bowen has practiced veterinary medicine in England and Texas. She lives in Blacksburg now, and answers local pet owners' questions every week in The Roanoke Times and roanoke.com.

Recent columns

• Bacteria can cause ear infections in cats
• Chiari is a malformation of the back for some spaniels
• Your plant smells like a great spot to ...
• Sting salve: meat tenderizer

Q What is the latest theory about that annoying habit of head-shaking in horses? I have a warmblood who does this and it is getting worse. I have tried all the usual remedies to no effect.

A The cause of the equine head-shaking syndrome has puzzled research workers for many years and a number of theories have been suggested as to its cause.

The latest theory to gain ground among research workers is that it involves irritation of the trigeminal nerve in the head. The specific trigger or cause of the irritation may vary from horse to horse and can include a wide range of causes. These include allergies, changes in the weather and humidity.

More obvious causes such as a tooth problem or sinus inflammation also can lead to this problem. Dr. John Madigan of the University of California-Davis veterinary school is a leading expert on the equine head-shaking syndrome and has suggested that because most cases occur in the spring, and are more common in geldings, it may be related to a change in hormone levels that rise naturally in the spring.

Madigan has had some success in treating the condition with a therapeutic hormone cocktail in seasonal head-shakers.

It is important to have the horse examined by a veterinarian to ensure that there is no physical reason for the condition.

If all other causes have been ruled out, and particularly if the problem is seasonal, then it may be the fault of irregular nerve impulses from the trigeminal nerve being over-stimulated by an overproduction of gonadotropin hormones.

The horse has a persistent tingling or painful sensation to the muzzle and face that can be intolerable and does not respond to painkillers. Many people have found the use of a nose net to be helpful in reducing the amount of head-shaking.

These nets provide a mechanical stimulus to the irritated nerves of the face and act as a counterirritant. These have proved to be useful in 50 percent of cases. It is rare for the problem to be caused by the owner, bridle, bit, or use of the horse. Horses should not be punished for head-shaking because it is not a vice.

Q When were dogs first used to diagnose cancer in people? This seems incredible to me or is it just an old wives' tale?

A The first report was in the British medical journal The Lancet in 1989 of a border collie and Doberman mix who tried repeatedly to bite a mole from its owner's thigh.

This was subsequently found to be a malignant melanoma. The dermatologist felt that the dog had saved its owner's life by making her have treatment while the melanoma still was curable.

There are reports of dogs who have been able to diagnose cancer, not only of skin lesions such as melanomas and basal cell carcinomas, but also of breast, lung and bladder cancers.

In 2004, there was an experiment conducted in which dogs were found to be able to detect bladder cancer by merely sniffing the patient's urine.

Dogs can tell when a diabetic is either hypoglycemic or hyperglycemic and will react persistently until steps are taken to bring the blood sugar of the diabetic back to normal. Dogs also can detect when a person is going to have an epileptic seizure. This is particularly useful in the case of children.

To date, nobody has been able to find out how dogs are able to detect cancer. In the case of lung and breast cancer, it is thought that subtle changes in exhaled breath alerted the dogs to the cancer, and this certainly could be the case with diabetics and their changes in blood sugar levels.

Changes in movement and body language may alert the dog to the onset of a seizure sometime before the changes become obvious to people. But how dogs can diagnose skin cancers often through the clothing remains a puzzle.